Wi-Fi may not be the first wireless technology one thinks of when considering low power IoT applications, but it should be. In this Q&A, Silicon Labs’ senior product manager for Wi-Fi products Siddharth Sundar discusses Wi-Fi's advantages and challenges that developers should keep in mind when choosing the right approach to wireless IoT.
Being a widely deployed protocol with approximately 13 billion deployed devices means that Wi-Fi connectivity is available in most home and commercial/office environments. This avoids the need for a gateway and lets devices be cloud connected without needing new infrastructure. Wi-Fi is also highly interoperable, so you can have confidence that your devices will connect to most Wi-Fi networks out there. The higher data rates and range offered by Wi-Fi also enable a wider range of applications.
Wi-Fi has significantly higher data throughput than most other IoT wireless communication protocols – often 10-100x higher, allowing it to tackle higher throughput applications like audio and video. The broad deployment and range of Wi-Fi is also a significant benefit compared to many other protocols.
These benefits do come at a cost. Wi-Fi products typically have higher power consumption and higher implementation costs than IoT specific protocols like BLE and Zigbee, since the range and throughput offered by Wi-Fi demands higher design complexity. However, most of this design complexity can be managed through using pre-certified modules, and the cost and power consumption of Wi-Fi devices is decreasing to a point where it is competitive for many IoT applications.
There are a few key reasons why 802.11n (Wi-Fi 4) may be better suited for most IoT applications than 802.11ac-based products (Wi-Fi 5). First, 802.11ac is based on 5 GHz versus 802.11n which supports both 2.4 GHz and 5 GHz. 2.4 GHz offers more range and better object penetration compared to 5 GHz. This is a key benefit in home environments with multiple walls and barriers.
Also, IoT Wi-Fi devices like Silicon Labs transceivers and modules are designed with enhanced RF selectivity to maintain reliable communication even in the presence of blockers such as nearby APs, 802.15.4 and Bluetooth devices. The below figure illustrates how advanced interference mitigation techniques help overcome the channel limitations related to the 2.4 GHz band. Learn more in Wi-Fi Learning Center.
One final point, the cost and power consumption of 802.11ac based systems is higher due to the higher protocol complexity. While it does provide enhanced throughput, the data rates provided by 802.11n are more than sufficient for most IoT applications including audio and security/IP camera video streaming.
There are a number of ways to reduce power consumption using Wi-Fi:
Wi-Fi solutions have traditionally been more complex and larger than solutions for Bluetooth. However, this gap is reducing, and there are increasingly smaller, optimized solutions available for Wi-Fi. This new class of IoT Wi-Fi devices takes advantage of Moore’s law to deliver higher performance, and eliminates size/cost adding features like MIMO. For example, Silicon Labs has a pre-certified Wi-Fi SiP module (including a Wi-Fi Radio, RF, XTAL and antenna) in a 6.5 mm x 6.5 mm package, which allows you to add Wi-Fi to small form factor devices.